GB1365226A - Seal mechanisms - Google Patents

Abstract

1365226 Rotary shaft seals; valves CHARLES-WESTON & CO Ltd 23 May 1973 [30 May 1972] 25130/72 Headings F2B and F2V In sealing means for apparatus, e.g. a clutch device 47, in which operating fluid is transmitted through a rotary shaft 11 from a stationary pipe comprising a casing 10 having a fluid inlet and encircling the shaft, a sleeve 16 rotatable with the shaft, and spring-loaded end face seals 41 housed in a chamber 21 between the casing and the sleeve to seal the gap therebetween, the sleeve is provided with valve means 24A, 24B which allows passage of fluid to and from the rotary shaft below a predetermined shaft speed but prevents it at or above that speed to enable the pressure in the chamber to be relieved. The casing is connectible to a source of air pressure through an inlet pipe 14 and a manually operable valve having feed, exhaust and off positions A, B and C respectively. An axial bore 19 in the shaft communicates via a radial bore 20 with a chamber 18 between the shaft and the sleeve. The valve 24A is centrifugally operated to close at the predetermined shaft speed. The valve 24B is a check valve allowing air to pass to the bore 19 and has a stem 25 abutting an actuating ring 26 located by pins 27 and urged by springs 29 against a manually operable emergency valve 33 disposed diametrically opposite the pins. The stem 32 of valve 33 has a wedge-shaped head that normally engages a corresponding groove 30 in the ring 26. A bore 37 in the stem opens the chamber 18 to atmosphere through a passage 38 in the valve body 34 when the valve is open as in Fig. 2. The end face seals comprise rotary sealing rings 43 urged by springs 44 into contact with stationary rings 45. In operation, when the clutch drive shaft 45 rotates slowly, air is admitted to the shaft bore 19, and shaft 11 rotates at the drive shaft speed. Acceleration of the drive shaft to normal speed causes the centrifugal valve 24A to close and the valve 15 may then be operated to reduce the pressure in chamber 21 to atmospheric, thus relieving the load on the seals 41, whilst maintaining the pressure in the device 47. In an emergency pressure may be released in the bore 19 by operating valve 33. In addition, a further pressure release valve (not shown) may be fitted in the chamber 21.